Black Box when selected? (Forms

Hey guys. 

Don't suppose anyone could offer me assistance?

I'm trying to include forms on my website, everything is running fine. Expect when options are selected it shows as a black box, I've tried tweaking the colours in the colour scheme but I don't seem to be having any joy. (I've attached a screenshot of how it appears once selected.)

Just to note, I am no good with coding, just looking at codes gives me a headache.

Thanks in advance.

Try changing the button in site styles, click the edit section, choose a button,  select the paintbrush icon at the top right corner then select a color theme. You may have to experiment to get an active button color you like.